The commentators wouldn't know anything. Tom saying something big is coming is significant, but I also wouldn't expect him to know the marketing schedule a full year in advance. At best I'd say DOA6 is announced at PSX (Dec 9) with a limited playable build at NEC a week later.
Again, there's basically no media presence at NEC, especially compared to the media presence at PSX. It just wouldn't make sense to announce DOA6 at NEC when it's a week after PSX.
As for the game being PS4 exclusive, didn't TN have huge issues making DOA5 run properly on Xbox One? Then you have Dissidia, Nioh and DOAX being PS4 exclusive. There are some other factors that made those first two exclusive, but still. I won't complain at all if DOA6 hits Xbox as well, it just wouldn't surprise me at all to see it PS4-exclusive.
I can agree with the bolded. But it could still work otherwise since DOA doesn't have the star power it once had, yet still has regular appearances in tournaments, and is still respected there. PSX is also a different audience from TGS or E3.
About the exclusive talk, the X1 version was patched if I remember well, and had just the usual issues compared to other PS4 multiplats (lower resolution and some bugs).
Dissidia has always been a playstation exclusive, and is coming after more than a year of arcade exclusivity, Nioh was a special deal similar to Ninja Gaiden back on Xbox, and there was no audience for DOAX (and other japanese niche games) on X1, and didn't leave asia on top of that.
DOA is a classic fighting game, it's really different. There's a market for that on every platform, just like DOA Dimensions was on 3DS and DOA5+ was on Vita. I'd be extremely surprised if it was an exclusive when it's not targeting a really specific audience.